USGS:Science for a changing world
Geologic Division

Gulf of Mexico / Southeast Tidal Wetlands

Project Leader:
Ellen Raabe
600 Fourth Street South
St. Petersburg, FL 33701-4846
Phone: (727) 803-8747 ext. 3039
Fax: (727) 803-2032

The Issue

The project is investigating the loss of coastal wetlands and adjacent uplands in order to determine long-term change in wetlands and to provide a model for determining areas that are most vulnerable to loss because of combinations of human and natural impacts. The project will investigate critical wetlands along the Gulf of Mexico and southeastern U.S. coast cooperatively with USGS BRD, NOAA, FWS, and state agencies. The investigation is determining change over historical time at these regions, identifying the significance of change over the past 20 years when detailed satellite imagery is available, and match these changes to known factors such as sea level change, sedimentation, and human impacts. A landscape evolution model will be applied to evaluate existing studies and understanding of critical processes for assessing change and vulnerability of coastal environments with development and projected rises in sea level.

We have considerable concern about the potential loss of wetlands in Florida in the future, when minor retreat has occurred over the last century.

How the USGS is addressing this issue

This project has the following goals:
  1. To document the changes in a set of critical and representative wetlands in the Gulf of Mexico and southeastern U.S. in order to integrate different time scales to determine historical long-term change.
  2. To compare these changes to natural and human impacts occurring in those regions, such as development, habitat modification, sea level change, and varying climatic conditions.
  3. To model the response of the wetlands to the changes using existing understanding of wetlands response to various processes and evaluate the model for the potential to identify wetlands that are vulnerable to decline or loss.
The project will examine the patterns and areal extent of change from NOAA T-sheets, photography, and satellite imagery. We will look at elevation patterns, current sedimentation rates, examine cores for significant environmental change in historical time using peat and palynological studies, and determination of elevation change from sedimentation erosion tables (SET’s) and sedimentation from lead-210 and radiocarbon dates. During the course of the project, new satellite sensors are expected to be launched, and we will work closely with NOAA C-CAP to incorporate these sensors into existing Landsat data set using C-CAP protocols (Dobson et al., 1995).

Planned Activities

  1. To document change in wetlands over historic time periods from satellite imagery, photography, and other sources. This effort involves the use of Landsat Thematic Mapper (TM) imagery from 1984 to the present, Landsat Multi-Spectral Scanner (MSS) imagery from 1973 to the 1992, aerial photography from selected time periods (typically 1950’s to present), and T-sheets (topographic shoreline sheets) from the Coastal and Geodetic Survey in the late 1800’s. The Landsat imagery provides vegetation changes, photography and T-sheets provides shoreline and upland boundary changes.
  2. To identify changes in the marshes over historic times using studies of vertical accretion and deposits. Accretion is measured currently through sedimentation-erosion tables (SETs), and in the past from Pb-210 studies. Pollen and vegetation analyses will identify changes in the environments. Basic sedimentological analyses will identify major shifts in deposition.
  3. Document elevation changes associated with environmental and geological shifts.
  4. To identify processes causing change through high temporal resolution data, and distinguish decadel changes from inter-annual changes. This incorporates the imagery and vertical change data together with information on sea level, precipitation, discharge, and major storms in the areas of interest. Stumpf, Raabe, USF students
  5. To model changes in the coastal environment by incorporating vertical accretion of marshes and changes in adjacent upland areas. By incorporating vertical accretion models for wetlands, with the aereal and vertical data, and vegetation responses in a GIS-based model we will simulate or hindcast changes observed over historic time. Successful hindcasting allows us to attempt to forecast environment change.

New Directions, Expansion of Continuing Project:

A side component may develop into a significant program: our processing of imagery, which includes the Suwannee River delta, has led to considerable interest on the part of WRD, University of Florida, and others. We have seen changes that may reflect the role of discharge in influencing vegetative health in the delta. The Suwannee has also received increasing attention because the possibility of water diversion for south Florida and because of deteriorating water quality along the coast, where a significant shellfish aquaculture program is developing.

We expect to expand the work in the Suwannee Delta, to support local management and leverage to obtain OFA funds.

We have begun examining the modeling capabilities for determining sea level change. Determination of the rate of loss of both uplands and wetlands is critical to understanding the implications of sea level rise. Accretion models for tidal wetlands have been developed, however these models have not yet entered the geographical predictions of land loss.

Accomplishments to Date

We have mapped imagery for South Carolina and for Florida for a 10-year period. Sedimentation- erosion table (SET) sites have been set up along the coast. Cores have been taken for dating and environmental change interpretation. We have evidence that in Florida, the 20-30 cm rise in sea level over the last 130 years has caused tidal wetlands to have increased in area at the expense of upland regions.

To date we have developed a map of land cover in 1986 and 1995 consistent with the NOAA C-CAP (Coastal Change Analysis Program). Arranging logistics with NOAA for confirmation has been a problem, but should be completed this year for a joint CD. Several proceedings papers, an OFR, and two journal articles have resulted.

We have obtained initial results of a lidar terrain mapping flight. The results indicate that in some areas of the marsh we can determine DEMs. The lidar also provide fine details of drainage and may provide a powerful tool for mapping aerial photography. We will evaluate the utility of lidar in determining subtle elevation differences in vegetated areas.

USGS Cooperators

  • USGS-BRD, Florida Biological Diversity Project, Leonard Perlstein (Gainesville).
    Using our processed imagery for detailed habitat mapping in the state of Florida.
  • NOAA C-CAP Program, Don Field and Dorsey Worthy, NOAA CSC (Charleston SC).
    Analysis of Florida Big Bend is being used as part of national mapping effort for coastal change. Our research into time series of change and impact of water level on imagery provides guidance for protocols.
  • USGS-BRD, National Wetlands Research Center, Don Cahoon, Elijah Ramsey, Richard Day (Lafayette LA).
    A complementary study on the linkage between wetlands sedimentation and vegetative health is being conducted concurrently. Also, we are exchanging information from complementary studies land cover change and elevation in St. Marks Florida and Louisiana.


Data Distribution:

Provided mapped and classified satellite imagery (two scenes covering ~35,000 square km) to the Biological Research Division, Gainesville, FL, for their mapping program in the Florida Biological Diversity project as part of the National Gap Analysis Program (March 1997).


The Tampa Tribune, 19 May 1997, ran a front-page article on the dieoff of Sabal palms (the Florida state tree) along the coast. This involved discussions with us and Kim Williams of University of Florida (a cooperator).


Nuttle et al. (18 authors including R.P. Stumpf), 1997. Forecasting the fate of coastal wetlands, Eos, in press.

Raabe, Ellen A. and Richard P. Stumpf, 1997, Determination of Long-term Change in the Big Bend Tidal Wetlands: Landscape-scale ecosystem evaluation with satellite imagery, Florida Big Bend Coastal Research Workshop: Toward a Scientific Basis for Ecosystem Management, William J. Lindberg, ed., University of Florida, Gainesville, FL, Technical Paper 88, pp. 41-42.

Raabe, Ellen A. and Richard P. Stumpf, 1997, Image Processing Methods: Procedures in Selection, Registration, Normalization and Enhancement of Satellite Imagery in Coastal Wetlands, U.S. Department of Interior, Geological Survey, Open-File Report 97-287, 29 pp. with 4 color plates.

Raabe, Ellen A. and Richard P. Stumpf, 1997, Assessment of acreage and vegetation change in Florida’s Big Bend tidal wetlands using satellite imagery, Proceedings of the Fourth International Conference: Remote Sensing for Marine and Coastal Environments, Volume I, 17-19 March, 1997, Orlando, FL, Environmental Research Institute of Michigan, Ann Arbor, MI, pp. 85-93.

Harris, M., M. Caldwell, J.D. Althausen, R.P. Stumpf, E.A. Raabe, 1997. Pre-processing methods of satellite imagery for coastal wetlands studies in the southeastern United States. Fourth International Conference on Remote Sensing for Marine and Coastal Environments, vol. 1, p. 642-648.

Stumpf, R.P. and J.W. Haines, 1998, Variations in tide level in the Gulf of Mexico and implications for tidal wetlands. Estuarine, Coastal and Shelf Science, vol. 46. P. 165-173.

Williams, K., K.C. Ewel, R.P. Stumpf, F.E. Putz, T.W. Workman, (submitted). Sea-level rise and coastal forest retreat on the west coast of Florida, USA. Ecological Monographs.

Recent Abstracts

Raabe, Ellen A. and Richard P. Stumpf, 1998, A Misleading Shoreline: historic trends in Florida’s Big Bend intertidal marsh, ASPRS-RTI Annual Conference Proceedings, March 30-April 3, 1998, Tampa, FL, p. 649.

Raabe, E.A., R.P. Stumpf, K. Williams, and J.L. Ladner, 1997, Tidal Wetland Response to Sea Level and Climatic Variability in the Florida Big Bend, 14th Biennial Estuarine Research Federation (ERF) International Conference: The State of Our Estuaries, Abstracts, ERF ‘97 October 12-16, 1997, Providence, R.I., p. 149

Harris, M. R.P. Stumpf, E.Raabe, 1998, Utilizing principal components analysis and image time series for analysis of trends in Florida’s Big Bend coastal marsh. ASPRS-RTI Annual Conference Proceedings, March 30-April 3, 1998, Tampa, FL.

Cox, D. R.P. Stumpf, E.A. Raabe, 1998, NDVI applications as an aid in classification and the objective identification of ecotones. ASPRS-RTI Annual Conference Proceedings, March 30-April 3, 1998, Tampa, FL.

Raabe, Ellen A. and Richard P. Stumpf, 1998, Climatic Variability and Landscape Change on a Marsh Shoreline, 1998 ERIM Conference, Fifth International Conference, Remote Sensing for Marine and Coastal Environments, 5-7 October, 1998, San Diego, California, Session G.

Gulf of Mexico Tidal Wetlands website:

U.S. Department of the Interior, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
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Updated May 06, 2013 @ 09:24 AM (THF)